Hard disk drives are used in almost all computer system operations. In fact, most computing systems are not operational without some type of hard disk drive to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the hard disk drive is a device which may or may not be removable, but without which the computing system will generally not operate.
The basic hard disk drive model was established approximately 40 years ago and resembles a phonograph. That is, the hard drive model includes a plurality of storage disks or hard disks vertically aligned about a central core that spin at a standard rotational speed. A plurality of magnetic read/write transducer heads, for example, one head per surface of a disk, is mounted on the actuator arm. The actuator arm is utilized to reach out over the disk to or from a location on the disk where information is stored. The complete assembly, e.g., the arm and head, is known as a head gimbal assembly (HGA).
In operation, the plurality of hard disks is rotated at a set speed via a spindle motor assembly having a central drive hub. Additionally, there are channels or tracks evenly spaced at known intervals across the disks. When a request for a read of a specific portion or track is received, the hard disk drive aligns a head, via the arm, over the specific track location and the head reads the information from the disk. In the same manner, when a request for a write of a specific portion or track is received, the hard disk drive aligns a head, via the arm, over the specific track location and the head writes the information to the disk.
Over the years, refinements of the disk and the head have provided great reductions in the size of the hard disk drive. For example, the original hard disk drive had a disk diameter of 24 inches. Modem hard disk drives are generally much smaller and include disk diameters of less than 2.5 inches (micro drives are significantly smaller than this dimension). Refinements also include the use of smaller components and laser advances within the head portion. That is, by reducing the read/write tolerances of the head portion, the tracks on the disk can be reduced in size by the same margin. Thus, as modern laser and other micro recognition technology are applied to the head, the track size on the disk can be further compressed.
A second refinement to the hard disk drive is the increased efficiency and reduced size of the spindle motor spinning the disk. That is, as technology has reduced motor size and power draw for small motors, the mechanical portion of the hard disk drive can be reduced and additional revolutions per minute (RPM) can be achieved. For example, it is not uncommon for a hard disk drive to reach speeds of 15,000 RPM. This second refinement provides weight and size reductions to the hard disk drive and increases the linear density of information per track. Increased rates of revolution also provide a faster read and write rate for the disk and decrease the latency, or time required for a data area to become located beneath a head, thereby providing increased speed for accessing data. The increase in data acquisition speed due to the increased RPM of the disk drive and the more efficient read/write head portion provide modern computers with hard disk speed and storage capabilities that are continually increasing.
A third refinement to the hard disk drive is the use of perpendicular recording. Previously, bits, e.g., represented as different alignments of magnetized portions of a recording media, or as transitions of such portions, were recorded substantially in the plane, e.g., parallel to the plane, of the rotating recording media. With a system of perpendicular recording, the bits are recorded perpendicular to the plane of the recording media, resulting in vastly improved storage density. For example, perpendicular recording is believed to be capable of delivering up to ten times the storage density of longitudinal recording, for the same recording media.
FIG. 1 (conventional art) illustrates a side sectional view of a recording element and media, as are utilized for perpendicular recording in a hard disk drive. Recording element 100 is a monopole inductive write element. Disk 110 comprises a recording media 130, and a soft underlayer 120.
Recording element 100 comprises pole tip 105 and return pole 107. Pole tip 105 is a relatively small feature that concentrates a magnetic field 140 in the area of the recording media 130. The concentrated magnetic field 140 is sufficient to magnetize a portion of the recording media 130. Return pole 107 is a relatively large feature. The magnetic field 140 density near return pole 107 is insufficient to magnetize a portion of the recording media 130. Consequently, “bits” are written by, and in the vicinity of, recording pole 105.
The design and construction of recording element 100, and more particularly pole tip 105, are critical to the performance of a disk drive. For example, pole tip 105 must comprise necessary magnetic properties to effectively create the recorded bits. In addition, pole tip 105 also must comprise necessary aerodynamic properties to form an air bearing surface (ABS) to “fly” over the disk. It is appreciated that the design and manufacture of pole tip 105 is complex, and that numerous engineering tradeoffs in the areas of materials, shape, manufacturing techniques and the like interact with one another. Consequently, improvements in the design and manufacture of disk drive recording elements are continually sought.